Micro-Polluted Surface Water Treatment by PAC-MBR Process

A kind of hybrid membrane process, which integrated powdered activated carbon (PAC) with membrane bioreactor (MBR), was designed for bench scale experiment for micro-polluted surface water treatment. Molecular weight analysis was used to evaluate the efficiency of each unit process and the integration of them. The result of analysis indicated that organic molecules in the treated water from PAC-MBR process were concentrated on the section of below 1000, while PAC adsorption could enhance the removal efficiency of this section due to the high percent of biodegradation recalcitrant organic matter with low molecular weight. It was demonstrated that PAC adsorption and biological treatment promoted each other in PAC-MBR process, with a removal efficiency of 70% for COD Mn and UV 254, 100% for UV 410 and 92% for ammonia nitrogen in its stable stage.

Coagulation of micro-polluted Pearl River water with IPF-PACls

Water samples collected from early March 2001 to the end of April 2002 at the branch of Pearl River around the Guangzhou City were analyzed for its micro-polluted characteristics. The coagulation behavior of polyaluminum chlorides(PACls) was then examined focusing on the effect of primary water quality and speciation distribution. The results showed that PACls exhibit better coagulation efficiency than alum in accordance with the different speciation. The turbidity removal property of PACls is evidently better than alum at low dosage. While in neutral zone(about 6.5—7.5), the turbidity removal of PACls decreases owing to the restabilization of particles at higher dosage. The organic matters in raw water exhibit marked influence on coagulation. In acidic zone, organic matters complex with polymer species and promote the formation of flocs. With an increase in pH, the complexation of organics with polymer species gradually decreases, and the removal of organics mainly depends on adsorption. The effect is evidently improved with the raise of B value.

Preparation of New Poly Silicate Iron Coagulants and Their Coagulation Property on Micro-polluted Water

The sodium silicate, ferric chloride, ferrous sulfate, sodium chlorate and other common inorganic materials were used to synthesize two new poly silicate iron coagulants： Polysilicate Ferric Chloride （PFSiC） and Polymeric Ferric Silicate Sulfate （PFSiS）. Their coagulation effect on micro-polluted water was compared with the poly ferric choride （PFC） saled in the market. The results showed that turbidity, organic matter, total phosphorus, total nitrogen removal rate ofPFSiC, PFSiS coagulant were better than PFC on micro-polluted water treatment at the same dosage. The coagulation effect of PFSiC was the best. The surface morphology of three coagulants was observed by scanning electron microscopy （SEM）, and the coagulation mechanism was discussed preliminarily.

Functional Capsules Encapsulating Molecular-Recognizable Nanogels for Facile Removal of Organic Micro-Pollutants from Water

A novel method has been successfully developed for the facile and efficient removal of organic micro-pollutants(OMP)from water based on novel functional capsules encapsulating molecular-recognizable nanogels.The functional capsules are composed of ultrathin calcium alginate(Ca-Alg)hydrogel shells as semipermeable membranes and encapsulated poly(N-isopropylacrylamide-co-acrylic acid-g-mono-(6-ethanediamine-6-deoxy)-β-cyclodextrin)(PNCD)nanogels withβ-cyclodextrin(CD)moieties as OMP capturers.The semipermeable membranes of the capsules enable the free transfer of OMP and water molecules across the capsule shells,but confine the encapsulated PNCD nanogels within the capsules.Bisphenol A(BPA),an endocrine-disrupting chemical that is released from many plastic water containers,was chosen as a model OMP molecule in this study.Based on the host–guest recognition complexation,the CD moieties in the PNCD nanogels can efficiently capture BPA molecules.Thus,the facile and efficient removal of BPA from water can be achieved by immersing the proposed functional capsules into BPA-containing aqueous solutions and then simply removing them,which is easily done due to the capsules’characteristically large size of up to several millimeters.The kinetics of adsorption of BPA molecules by the capsules is well described by a pseudo-second-order kinetic model,and the isothermal adsorption thermodynamics align well with the Freundlich and Langmuir isothermal adsorption models.The regeneration of capsules can be achieved simply by washing them with water at temperatures above the volume phase transition temperature of the PNCD nanogels.Thus,the proposed functional capsules encapsulating molecular-recognizable nanogels provide a novel strategy for the facile and efficient removal of OMP from water.

Performance of BAC process for treatment of micro-polluted water

Biological activated carbon (BAC) has been developed on the granular activated carbon by immobilization of selected and acclimated species of bacteria to treat the micro-polluted water. The BAC removal efficiencies for nitrobenzene, permanganate index, turbidity and ammonia were investigated. Effects of shock loading and SEM (Scanning Electron Microscope) observation on BAC were studied. Backwashing and its intensity of BAC were also discussed. The results showed that BAC took short time to start up and recover to the normal condition after shock loading. The shock loading studies showed that the removal efficiency of BAC was not completely inhibited even at high concentration of nitrobenzene. Backwashing performed once every 10-20 d, or an average of 15 d. Backwashing intensity was 12-14 L/(s·m2) with air and 3-4 L/(s·m2) with water.

Surface flow constructed wetland with composite plant bed for pretreatment of micro-polluted Yellow River raw water in China

In order to investigate the feasibility of pretreating the micro-polluted Yellow River raw water by constructed wetland, an experiment was conducted using a surface flow constructed wetland with composite plant bed. The contamination removal efficiency and their trends in the wetland treatment system were studied under different hydraulic loading rates(HLR). The contamination removal efficiencies were compared according to the seasonal change under optimum HLR. The result shows that in the same season, under different hydraulic loadings ranging from 2 to 6 m3/(m2·d) at the same period, the best HLR is 4 m3/(m2·d) in the experimental system. The average removal rates of COD, TN, ammoniacal nitrogen(NH4+-N), and TP in the constructed wetland are 38.37%, 45.97%, 39.86% and 41.69%, respectively. According to China Standard for Surface Water Resources (GB3838-2002), mean effluent of COD, TN, NH4+-N and TP can nearly reach Grade Ⅲ, GradeⅤ, GradeⅠand GradeⅠ, respectively. Furthermore, treatment efficiency of the system in summer is obvious higher than that in other seasons. The expenditure of constructing the constructed wetland with the average treating capacity of 176 m3/d and lifetime of 20 years is 17075.00 RMB. The average disposal cost is summed up to 0.17 RMB/m3, which shows that the pretreatment of the micro-polluted Yellow River raw water by constructed wetland is feasible.

The Occurrence and Prevention of Filamentous Algae in Ecological Purification System of Micro-polluted Water

[ Objective ] The aim was to study the influence of filamentous algae on the process of water ecological purification. [ Method ] The occurrence mechanism of filamentous algae and its ecological system were summarized and analyzed. Considering the ecological purification in north- ern Jiangsu, the occurrence and prevention of filamentous algae in water, the method to prevent filamentous algae in polluted water was discussed. [ Result] The results showed that by measures of improving planting density, regular harvesting, and water flow state control before the filamentous algae blooming period, together with improving local pH value, light interference and ecological control during the blooming period, can effectively control the filamentous algae blooming. [ Condusion] The study of the happening mechanism of filamentous algae provided theoretical references and the technical basis in the work of filamentous algae prevention and control.

Application of Green Technology Using Biological Means for the Adsorption of Micro-Pollutants in Water

It is true that the world we have today is not the world we use to know. The Covid-19 pandemic has paralyzed all sector, hence the need for safety and enabling environment for mankind is of high importance. Adsorption technology is far the best and cheapest treatment technology for water and has extensively proven its worth for the uptake of micro-pollutant from surface, ground and water which are the major channels of home water. Over the years activated carbon is considered as the most common and universally used adsorbent for the eradication of different types of micro-pollutants from water. The contamination of surface water by micro-pollutant is a potential threat for the production of high quality and safe drinking water. Adsorption operation onto granulated activated carbon (GAC) in fixed-bed filters is often applied as a remedying step in the synthesis of safe and drinkable water. Activated carbon actively tends to act as a carrier material for a thin usually resistant layer of microorganisms (mostly bacteria) that forms on the coat of various surfaces (biofilm), hence biological simplification can be an alternative removal approach that can be adopted in granulated activated carbon filters. To evaluate the capacity of biofilm to biologically simplify micro-pollutants, it is very imperative to distinguish adsorption from biological simplification (biodegradation) as a removal mechanism. Experiment was carried out under the operating condition of a temperature range of 6?C to 20?C with biologically activated and autoclaved GAC to assess the biological simplification by the biofilm adsorbed on the GAC surface. Five micro-pollutants were selected as model compounds, of which some of them were biologically simplified by the GAC biofilm. Additionally, we observed that temperature can increase or decrease adsorption. Conclusively, comparison was made on the adsorption capacity of granulated activated carbon used for more than 50,000 beds.

Oil Pollutants Degradation of Nano-MgO in Micro-Polluted Water

The removal of oil pollutants from water and purifying process of oil-polluted water are studied through catalytic degradation method with nano-MgO. The results indicated that catalytic degradation effect of nano-MgO on the oil pollutants was associated with dosage of nano-MgO, pH and water temperature. When oil content was 1.8 mg/L, 0.17 g nano-MgO was used and the removal rate of oil was 93.92%. Furthermore, nano-Mgo was a non-photosensitive catalyst. GC/MS analysis showed that the amount of petroleum-based pollutants in water was reduced 73.77% from the previous 61 kinds to 16 kinds, and the total peak area was reduced 96.05% after catalytic degradation of nano-MgO. Therefore, nano-MgO has an excellent effect on the catalytic degradation of oil pollutants and can be applied in the treatment of oil wastewaters.

17α-Ethinylestradiol removal from water by magnetic ion exchange resin

Magnetic ion exchange(MIEX) resins have received considerable attention in drinking water treatment due to their fast and efficient removal of dissolved organic carbon(DOC). Two types of mechanisms, i.e., ion exchange,reversible and irreversible adsorption, may occur during pollutants removal by MIEX. This work examined the removal mechanism of 17α-Ethinylestradiol(EE2) by MIEX. As one of typical estrogen micro-pollutants,EE2 existed as neutral molecule in natural water, and its charge density was close to zero [(0.00000219 ±0.00000015) meq·(μg EE2)^(-1)] based on the potentiometric titration method. However, the removal of EE2 by MIEX was much higher than that of other micro-pollutants previously reported. Multi-cycle adsorptionregeneration experiments and ion exchange stoichiometry analysis were conducted to elucidate the removal mechanism of EE2 by MIEX resin. The results suggested that the main removal mechanism of EE2 by MIEX was ion exchange instead of reversible micro-pore adsorption. The experimental analysis based on Donnan theory indicated that the internal micro-environment of resin beads was alkaline, in the alkaline environment EE2 would be ionized into negatively charged groups. As a result, ion exchange reaction occurred inside the pore of MIEX resin, and the removal process of EE2 by MIEX was dominated by the ion exchange reaction.

Removal of bentazone from micro-polluted water using MIEX resin:Kinetics,equilibrium,and mechanism

The contamination of surface and ground water by bentazone has attracted increasing global concern in recent years. We conducted a detailed investigation using MIEX resin to eliminate bentazone from waters. Batch experiments were carried out to evaluate the effect of process parameters, such as retention time, resin amount, and initial pesticide concentration, on removal efficiency of bentazone. Results showed the sorption process was fast and bentazone could be efficiently removed in 30 minutes. The kinetic process of bentazone sorption on MIEX resin was well described by pseudo second-order model and intraparticle diffusion was the rate controlling step. The MIEX resin possessed the highest sorption capacity of 0.2656 mmol/mL for bentazone according to Langmuir fitting, Bentazone is a hydrophobic ionizable organic compound, and both ionic charge and hydrophobic aromatic structure governed the sorption characteristics on MIEX resin. The different removal efficiencies of ionic and non-ionic pesticides, combined with the charge balance equations of bentazone, SO4^2-, NO3- and Cl-, indicated that removal of bentazone using MIEX resin occurred primarily via ion exchange.

Sulfur-based autotrophic denitrification from the micro-polluted water

Eutrophication caused by high concentrations of nutrients is a huge problem for many natural lakes and reservoirs. Removing the nitrogen contamination from the low C/N water body has become an urgent need. Autotrophic denitrification with the sulfur compound as electron donor was investigated in the biofilter reactors. Through the lab-scale experiment,it was found that different sulfur compounds and different carriers caused very different treatment performances. Thiosulfate was selected to be the best electron donor and ceramsite was chosen as the suitable carrier due to the good denitrification efficiency, low cost and the good resistibility against the high hydraulic loads. Later the optimum running parameters of the process were determined. Then the pilot-scale experiment was carried out with the real micro-polluted water from the West Lake, China. The results indicated that the autotrophic denitrification with thiosulfate as electron donor was feasible and applicable for the micro-polluted lake water.

Screening for 26 per-and polyfluoroalkyl substances(PFAS)in German drinking waters with support of residents

The occurrence of per-and polyfluoroalkyl substances(PFAS)in water cycles poses a challenge to drinking water quality and safety.In order to counteract the large knowledge gap regarding PFAS in German drinking water,89 drinking water samples from all over Germany were collected with the help of residents and were analyzed for 26 PFAS by high-performance liquid chromatography with tandem mass spectrometry(HPLC-MS/MS).The 20 PFAS recently regulated by sum concentration(PFAS_(∑20)),as well as six other PFAS,were quantified by targeted analysis.In all drinking water samples,PFAS_(∑20 )was below the limit of 0.1μg/L,but the sum concentrations ranged widely from below the limit of quantification up to 80.2 ng/L.The sum concentrations(PFASP4)of perfluorohexanesulfonate(PFHxS),perfluorooctanesulfonate(PFOS),perfluorooctanoate(PFOA),and perfluorononanoate of 20 ng/L were exceeded in two samples.The most frequently detected individual substances were PFOS(in 52%of the samples),perfluorobutanesulfonate(52%),perfluorohexanoate(PFHxA)(44%),perfluoropentanoate(43%)and PFHxS(35%).The highest single concentrations were 23.5 ng/L for PFHxS,15.3 ng/L for PFOS,and 10.1 ng/L for PFHxA.No regionally elevated concentrations were identified,but some highly urbanized areas showed elevated levels.Concentrations of substitution PFAS,including 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate and 2,2,3-trifluor-3-[1,1,2,2,3,3-hexafluor-3-(trifluormethoxy)propoxy]-propanoate(anion of ADONA),were very low compared to regulated PFAS.The most frequently detected PFAS were examined for co-occurrences,but no definite correlations could be found.

Nitrification performance of nitrifying bacteria immobilized in waterborne polyurethane at low ammonia nitrogen concentrations

Suspended and waterborne polyurethane immobilized nitrifying bacteria have been adopted for evaluating the effects of environmental changes, such as temperature, dissolved oxygen （DO） concentration and pH, on nitrification characteristics under conditions of low ammonia concentrations. The results showed that nitrification was prone to complete with increasing pH, DO and temperature. Sensitivity analysis demonstrated the effects of temperature and pH on nitrification feature of suspended bacteria were slightly greater than those of immobilized nitrifying bacteria. Immobilized cells could achieve complete nitrification at low ammonia concentrations when DO was sufficient. Continuous experiments were carried out to discuss the removal of ammonia nitrogen from synthetic micropollute source water with the ammonia concentration of about 1mg/L using immobilized nitrifying bacteria pellets in an up-flow inner circulation reactor under different hydraulic retention times （HRT）. The continuous removal rate remains above 80% even under HRT 30 min. The results verified that the waterborne polyurethane immobilized nitrifying bacteria pellets had great potential applications for micro-pollution source water treatment.

Nitrification and denitrification in biological activated carbon filter for treating high ammonia source water

Since the ammonia in the effluent of the tradi-tional water purification process could not meet the supply demand,the advanced treatment of a high concentration of NH4+-N micro-polluted source water by biological activated carbon filter(BACF)was tested.The filter was operated in the downflow manner and the results showed that the remov-ing rate of NH_(4)^(+)-N was related to the influent concentration of NH_(4)^(+)-N.Its removing rate could be higher than 95%when influent concentration was under 1.0 mg/L.It could also decrease with the increasing influent concentration when the NH_(4)^(+)-N concentration was in the range from 1.5 to 4.9 mg/L and the dissolved oxygen(DO)in the influent was under 10 mg/L,and the minimum removing rate could be 30%.The key factor of restricting nitrification in BACF was the influent DO.When the influent NH_(4)^(+)-N concentration was high,the DO in water was almost depleted entirely by the nitrifying and hetetrophic bacteria in the depth of 0.4 m filter and the filter layer was divided into aerobic and anoxic zones.The nitrification and degradation of organic matters existed in the aerobic zone,while the denitrification occurred in the anoxic zone.Due to the limited carbon source,the denitrifica-tion could not be carried out properly,which led to the accu-mulation of the denitrification intermediates such as NO_(2)^(−).In addition to the denitrification bacteria,the nitrification and the heterotrophic bacteria existed in the anoxic zone.

An assessment of trace metal pollution indicators in soils around oil well clusters

Due to the metallic ion constituents of crude oil,environmental levels of toxic metals are often exac-erbated when oil is spilt.Biseni community plays host to numerous oil production companies in Bayelsa state,Nigeria.However,the tendency for this clan to be flooded,particularly owing to its lowland fea-tures has continued to negatively impact on the environment.Sometimes,floods are accompanied by spilt residual oil that encroach living areas,thus leading to the contamination of open water bodies,underground water resources,and fish and crop farms.This study surveyed the impact of oil seepages from oil well clusters on the overall soil quality by applying trace metal pollution indicators.Trace metals were analyzed by atomic absorption spectrometry,and concentration ranged from 5893.0-6263.8 mg/kg,0.03e11.52 mg/kg,3.15e6.46 mg/kg,4.46e58.64 mg/kg,13.61e29.83 mg/kg,0.23e0.73 mg/kg,8.32 e20.69 mg/kg,and 4.24e9.31 mg/kg for iron,copper,nickel,lead,zinc,cadmium,chromium and cobalt respectively.Concentrations were within target limits stipulated by the Department of Petroleum Re-sources,Dutch standard limit and World Health Organization.Zinc and chromium showed the strongest correlation(r¼0.92,p<0.05)in the study area,whilst one-way ANOVA revealed equality(p>0.05)among the different sampling points.This is evidence that the field area is affected by similar contam-ination source.Whereas,the micro-pollutant metals depicted significant variability(p<0.05),probably due to the outlier concentration of iron.Overall,lead was the most contaminating metal,while location BNS2(0.3m)was the most considerably contaminated area.Enrichment factor revealed the anthropo-genic origination of lead.Index of geo-accumulation of lead ranged from moderate to heavy contami-nation,with lead recording very high contamination factor,and the degree of contamination depicting considerable risk,especially at the top soil.Pollution load index showed most contamination(moderately polluted)at BNS2.Quantification of contamination showed relative contamination for most locations,whereas potential ecological risk index mostly depicted low risk,apart from the exhibition of moderate risk of lead and cadmium at BNS2.Conversely,sum of pollution indices and risk index revealed low contamination and low risk respectively.